The invention disclosed herein pertains generally to tilting devices, and more particularly to a tilting device for a furnace positioned on rolling rockers.
It is known in the furnace art to use hydraulic cylinders as tilting devices for furnaces arranged on rolling rockers. Typically, these hydraulic cylinders are positioned on a side of a furnace opposite to a spout side, and are arranged between a foundation which supports the furnace, and the furnace itself. This is illustrated, for example, in the prospectus "Brown Boveri - Lichtbogenofen der Bauart SSKD" page 9, undated. A similar tilting device is described in FR-PS No. 2,113,198, where a rack is used instead of an hydraulic cylinder. Depending on the shape of the rocker geometry, the furnaces are either self-righting, i.e. stable, or have a backwardly directed moment. With respect to the former, double-acting cylinders or racks are employed, whereas with the latter it is possible to use single-acting cylinders.
A disadvantage of the known tilting devices is that a magnitude of a force necessary for a movement of a furnace depends on a length of a lever arm, which length is equal to a distance between a contact point of a pair of rolling rockers on a set of movable beams and a point of application of the foce. A length of the lever arm is especially small during a backward tilting of the furnace so that a correspondingly large force must be applied.
The disadvantage associated with the known tilting devices described above is particularly noticeable in the case of self-righting furnaces. With self-righting furnaces a double acting drive mechanism must pull the furnace into a backwardly tilted position against a righting moment. If hydraulic cylinders each having a piston are used as the drive mechanism, then an effective area over which hydraulic pressure may be applied is the area of the piston less a cross-sectional area of the associated piston rod. Therefore the cylinders must necessarily have relatively large dimensions. This is uneconomical and undesirable in terms of space considerations.
Accordingly, a primary object of the present invention is to provide a reliable tilting device for a furnace positioned on rolling rockers, which tilting device includes at least one drive mechanism whose dimensions are relatively small.
Apparatus for tilting a furnace arranged on rolling rockers, according to the present invention, includes at least one drive mechanism arranged adjacent a back-tilting side of the furnace, and at least one drive mechanism arranged adjacent a spout side of the furnace.
An advantage of the present invention is that, regardless of the tilting position of the furnace, either the at least one drive mechanism on the back-tilting side of the furnace or the at least one drive mechanism on the spout side of the furnace may take advantage of a relatively long lever arm. Thus a specified tilting moment may be achieved by means of a relatively long lever arm and relatively small force so that the drive mechanisms may have relatively small dimensions.
A preferred embodiment of the present invention includes drive mechanisms which employ hydraulic cylinders.
Another preferred embodiment of the present invention includes drive mechanisms which employ double-acting hydraulic cylinders, i.e., cylinders capable of exerting a force in either one of two opposed directions.
By using an hydraulic cylinder on each side of a furnace, the hydraulic cylinder on one side of the furnace is subjected to a compressive stress while the hydraulic cylinder on the other side of the furnace is subjected to a tensile stress. The forces exerted by each of the cylinders mutually reinforce one another, particularly with self-righting furnaces, because advantage is taken of the fact that the cylinder stressed in compression can produce a greater moment since it acts on a longer lever arm.
Yet another preferred embodiment of the present invention includes a drive mechanism having an hydraulic cylinder arranged on each side of a furnace, wherein a lower chamber of one cylinder is connected to, i.e., in communication with, an upper chamber of the other cylinder, and vice versa. This embodiment makes possible a simple control of the cylinders.
Yet a further preferred embodiment of the present invention includes two or more drive mechanisms at a spout side of a furnace with but one drive mechanism at a back-tilting side of the furnace, or two or more drive mechanisms at the back-tilting side of the furnace with but one drive mechanism at the spout side. This preferred embodiment of the present invention also includes two or more drive mechanisms respectively at the spout side of the furnace and at the back-tilting side of the furnace. This embodiment makes it possible to arrange the drive mechanism laterally in the region of the rolling rockers.